docs: def span_tokenize(self, s):
          """Return a list of integer offsets that identify sentences in the given text.
  
          :param string s: The text to tokenize into sentences.
          :rtype: iter(tuple(int, int))
          """
          if self._tokenizer is None:
              self._tokenizer = load_model(self.model)
          # for debug in tokenizer.debug_decisions(s):
          #     log.debug(format_debug_decision(debug))
          return self._tokenizer.span_tokenize(s)